In the commercial manufacture of ethyl alcohol from starchy substances by fermentation method, which enzymes stepwise complete the fermentation reaction.

Options

A. Diastase, maltase and zymase
B. Maltase, zymase and invertase
C. Diastase, zymase and lactase
D. Diastase, invertase and zymase

Answer

To answer the question regarding the enzymes involved in the commercial manufacture of ethyl alcohol from starchy substances through the fermentation method, we can break down the process into several key steps:

### Step-by-Step Solution:

1. **Starch Breakdown**:
- The first step in the fermentation process involves the breakdown of starch (a polysaccharide) into maltose (a disaccharide). This reaction is catalyzed by the enzyme **diastase**.
- **Chemical Reaction**:
\[ \text{Starch} \xrightarrow{\text{Diastase}} \text{Maltose} \]

2. **Maltose Conversion**:
- In the second step, maltose is further broken down into glucose (a monosaccharide) by the enzyme **maltase**.
- **Chemical Reaction**:
\[ \text{Maltose} \xrightarrow{\text{Maltase}} \text{Glucose} \]

3. **Glucose Fermentation**:
- The final step involves the conversion of glucose into ethyl alcohol (ethanol) and carbon dioxide. This reaction is catalyzed by the enzyme **zymase**.
- **Chemical Reaction**:
\[ \text{Glucose} \xrightarrow{\text{Zymase}} \text{Ethanol} + 2 \text{CO}_2 \]

### Summary of Enzymes:
- **Diastase**: Converts starch to maltose.
- **Maltase**: Converts maltose to glucose.
- **Zymase**: Converts glucose to ethyl alcohol and carbon dioxide.

### Final Answer:
The sequence of enzymes that catalyze the fermentation reaction in the commercial manufacture of ethyl alcohol from starchy substances is:
**Diastase, Maltase, Zymase.**

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